This invention relates to agents for and methods of treating synthetic fibers. The false-twisting speed for synthetic fibers are increasing fast in recent years. Most recently, false-twisting apparatus equipped with a non-contact type heater are coming to be used to carry out the false-twisting and draft processes simultaneously at a speed exceeding 1000 m/minute. At such a high yarn speed, the friction between the running yarn and guide members, static electricity which is generated on the running yarn and the abrasion of the running yarn against the sludge operate together in a compounded manner, causing abnormal tension variations in the yarn. If such an abnormal tension variation occurs in the running yarn, the false-twisted yarn which is obtained contains unevenness in filament fineness and uneven crystallinity, dyeing specks appearing as a result. Thus, this invention relates to agents for and methods of treating synthetic fibers with and by which occurrence of abnormal tension variations in running yarn can be prevented even during a false-twisting process at a high speed such that high-quality false-twisted yarns without having dyeing specks can be obtained.
Examples of prior art agents for treating synthetic fibers with which false-twisted yarns with good yarn quality can be obtained even by a high-speed false-twisting process include: (1) those having a polyether compound as principal component (Japanese Patent Publications Tokkai 49-31996, 50-155795, 50-199796, 4-24088 and 8-325949 and U.S. Pat. No. 4,044,541); (2) those using a polyether compound together with polyether modified silicon or a fluoride (Japanese Patent Publications Tokkai 60-181368, Tokko 6-21380 and U.S. Pat. No. 4,56,1987); and (3) those using a polyether compound together with an organic salt of organic carboxylic acid anions and quaternary ammonium cations having alkyl group or alkenyl group with 5 or less carbon atoms (Japanese Patent Publication Tokkai 9-111659). If such a prior art agent is used to carry out draft and false-twisting processes simultaneously at a high speed over 1000 m/minute and if, in particular, this is done by using a false-twisting apparatus of a recent type equipped with a non-contact type heater, however, it is not possible to fully prevent the occurrence of tension variations in the running yarn and false-twisted yarns of a sufficiently high quality cannot be obtained.
The problem, to which the present invention is addressed, is therefore that prior art agents for treating synthetic fibers cannot fully prevent the occurrence of tension variations in the running yarn in a high-speed false-twisting process and only false-twisted yarns of an inferior quality can be obtained.
This invention is based on the present inventors""s discovery that the above and other problems can be successfully addressed to if use is made of an agent for the treatment containing a lubricant, a non-ionic surfactant and a specified kind of amphoteric surfactant at a specified ratio and, in particular, if such an agent for the treatment is attached at a specified rate to spun synthetic fibers before they are subjected simultaneously to draft and false-twisting processes.